Questions tagged [electromagnetic-induction]

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Motion of a current carrying conductor

When a current carrying conductor is placed inside magnetic field, what motion does it take? Does the motion not occur and only Hall emf is obtained. Or if there is a motion due to Lorentz Force, ...
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Inducing electricity

I'm trying to under stand electromagnetic induction more and have been looking up all the ways to induce a coil with a magnet and keep only finding these three types of examples. I’m confused as to ...
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Induced EMF vs battery EMF

I am bit confused at whether induced emf and battery emf are same in nature differing just in their source. Does a potential gradient exist in case of induced emf as we have when a battery is ...
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Amateur student making a demo of electromagnetic induction via copper coil and magnet

I'm trying to observe electromagnetic induction by creating a copper coil solded to a diode led and waving an alnico magnet inside the copper coil's core. You can see my amateur setting below (...
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AC generator and the induced current

Why does increasing the area of a coil in an AC generator increases the induced current? Has it something to do with the force between different arms of the coil that is each exert a force on the ...
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Magnetic levitation: Attraction and Repulsion [closed]

How is the ball attracted ? https://www.youtube.com/watch?v=Y-wt3bME8nE How is the ball repulsed ? https://www.youtube.com/watch?v=OMuipEV-2Sw If the ball is made by metal, Will it be attracted or ...
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Why a Pan on induction heater not feel a repulsion force like a eddy current separator?

Eddy current separators are used to separate conductive and nonconductive particles where conductive particles feel a force and thrown away when they reach closer to a magnet. Why a conductive pan not ...
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Inductor with no resistance

Lets think about inductor that has no resistance. In initial condition, current is $I$, and the mag field is created only by inductor's current. And suppose that there is no battery connected. Now ...
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Ocean warming by induced electric current for wandering magnetic poles?

In a post on the co-rotation of Earth and its magnetic field (Does the geomagnetic field rotate?), John Rennie raised the point that, if Earth's magnetic field were rotating about its dipole axis, it ...
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How does a time varying magnetic field confined in a cylindrical region produces induced electric field even outside the cylindrical region?

We know from Faraday's Law of Electromagnetic Induction that due to Time Varying Magnetic Field (TVMF), a non conservative electric field will be induced. Now if we consider a cylindrical region in ...
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Velocity of strong magnet falling through pipe

What is the relationship between the radius of a non-magnetic tube/pipe and the terminal velocity of a magnet falling through it? I would appreciate if you can provide an equation.
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Faraday's Law and Electromagnetic Induction

Faraday's Law of electromagnetic induction states that the rate of change of magnetic flux linkage is proportional to the $\mathcal{emf}$ induced. For a conductor, the formula goes $$\mathcal{emf}=N\...
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What shape does the Induced Electric Field Lines take when in a region there is Non Cylindrical Time Varying Magnetic Field?

Everywhere in the literature I have across, I find that whenever the discussion of the Induced electric field comes, it is discussed around a cylindrical time-varying magnetic field. The induced ...
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How can current flow in a circuit if back emf is equal and opposite to applied voltage?

Ok, I've seen this question on this site before and other forums as well. A similar argument can be made if a resistor is connected to a voltage source through wires. The voltage across the resistor ...
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Why exactly does a current flow in an inductor oppose itself

So, I've understood that a current flow in an inductor produces 1) The original magnetic field along the direction of the curl E of the inductor. 2)Change in the magnetic field along the opposite ...
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EMF in Faraday's Law

I am really confused in the definition of EMF $\varepsilon$ in Faraday's Law. The example I saw was a loop of wire moving with velocity $\vec{v}$ inside a uniform magnetic field $\vec{B}$, which does ...
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Why is the electric field induced due to a Time varying magnetic field non-conservative?

As the title states, Why is the Electric Field which is induced due to a time varying Magnetic Field Non Conservative in nature ? Everywhere I read the answer that the line integral over a closed ...
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How does adding a second magnet on the other side of a coil affect induced voltage?

From what I understand, if you have a magnet moving with a relative velocity towards a coil, Lenz's law states that the current flow induced in the coil will create a magnetic field that opposes the ...
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Current through a loop symmetric about a current carrying wire

For part (b) where the current i is increasing, the answer is apparently that loops 1 and 3 have zero current induced. This doesn't make sense to me. The magnetic flux is changing through the area of ...
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Does the induced electric field do work on the incoming current?

When the current is increasing, the voltage drops across the inductor. I don't understand how the induced electric field is accomplishing this. Is the induced electric field doing work on the incoming ...
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Force per unit area on a solenoid

I am having a hard time attempting to eliminate constants of integration while solving maxwell's equations. Here is an example of a solenoid. Let a wire carrying current $I$ wind $n$ times per unit ...
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What actually is Induced emf?

I know how induced emf is produced and about Faraday law. But I am actually confused what we mean by induced emf? Is it the same example of emf in batteries where it is potential difference between ...
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Can Copper wires be used to increase linear acceleration of a ball within a circular pipe?

Imagine you have a metal ball within a pipe and copper wire wrapped around the pipe , wherein the pipe is connected circular. Can I pass current through the copper wire such that the linear ...
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Why is Motional Emf 0 when velocity is parallel to length

Why is Motional Emf 0 when velocity is parallel to length? Lets assume a case when B (magnetic field) is perpendicular to velocity and parallel to area vector of a circular coil . Now according to ...
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Different electric fields

What is the difference between an $electrostatic$ and a $non-electrostatic$ electric field?
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A point charge near a conducting cylinder

As we could figure out the point charge induced image charge on a conducting sphere in Jackson's book. Is there any way to figure out the point charge induced image charge form on a conducting ...
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Transformer in a circuit with a constant current source

I'm trying to understand the behavior of inductors and transformers and I was trying out some circuits. I'm having trouble understanding what happens when we use a current source and a transformer. ...
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How does an induced magnetic field generate a current, that causes a force?

I was reading about induction motors and stumbled across topics I used to tutor in college (namely, electricity and magnetism). I recalled all of the right-hand-rule-esque mechanisms from tutoring the ...
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Forces Acting On a Bar of Magnet Inside a Solenoid

If you have a solenoid placed like this: and you drop a magnet inside the coil will the change in acceleration of the bar of magnet inside the solenoid coil over change in time be 0? i.e. will the ...
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How does an electrical field influence a changing magnetic field?

I would like to know what happens in the following situation. (I am not planning on actually doing this - I just want to understand). Suppose I have a permanent magnet contained in a plastic capsule, ...
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Voltage between parallel capacitor plates

We know that $C=q/U$. We know that the voltage is the potential difference between the plates. If we have a capacitor on which we apply voltage, the one plate charges up and induces the other one with ...
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1answer
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Conservation of energy when placing two inductors next to each other

Say there is a circuit with a current source and an inductor. There is a current $i(t) = at$ going through the inductor. We now place a new circuit with an inductor and a resistor next to it. The ...
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Analytical expression for the EMF induced in a solenoid due to motion of a permanent magnet

A permanent magnet (cylindrical) of length (l) and radius(r) with velocity v(t) along z-axis as shown in the figure. I am looking for analytical expression for the induced emf in a coil with N turns, ...
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Drone's sufficient engine RPMs initiated by Magnetic Fields

I've seen many videos where magnets are used to initiate and boost RPMs. Most of them are fake, where people are using compressed air at the backstage. Did anyone of you actually tried to challenge ...
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On a rotating body is induced emf dependent on reference frame?

The magnetic field K is pointing inwards. Why does the induced emf differ between points B and D if the frame of reference is changed from B to A?
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Why can't a current carrying loop (curl of the electric field exists) produce a time varying magnetic field?

If a time varying magnetic field can give value to the curl of an electric field, why not the other way round? That is, why can't an enclosed loop with some emf produced (basically a current carrying ...
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What is the effect of charge of Sun induced on the Earth as compared to gravity?

As we know gravity is a less attractive force than the for of electric and magnetic fields. My question is where does the effect of magnetic field go while gravity has pull on earth. At this point ...
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Is this video about electrical transformers correct?

In this Youtube video, at around 5:10, it shows two graphs, when we have constant increase in voltage on the left, we have constant voltage on the right, but then when voltage stops changing on the ...
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Trouble understanding fractional flux linkage

My question is quite similar to one in the link: Flux linkage inside of a conductor. But I have trouble understanding any of the answers provided there. Specifically my question is the following: I ...
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1answer
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If a metal rod of length l is moved perpendicularly, in a straight line, inside a uniform magnetic field, will a emf be induced in the rod?

The magnetic flux density is constant, and the rod is being moved inside the field. And if an emf is induced, how does the flux linkage change in this rod? The cross sectional area of this rod ...
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Helmholtz coil construction and working

If I connect Helmholtz coil to ac( 220v, 50HZ) mains then is it means that the field it will generate is alternating field? Then how it generates a uniform magnetic field?
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A travelling field; Feynman lectures on Physics Volume 2

In Feynman's Lectures on Physics, volume 2, Chapter 18 (18-5), we look at the creation of a electromagnetic field, due to a moving infinite sheet of charge, By looking at the Maxwell equations ...
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How do you apply “flux-rule” in free space?

Faraday's law of induction states that, the tangential component of the force per unit charge$^*$; EMF produced in a loop of wire, is equal to change in the magnetic flux through the loop, $$\int_C \...
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Why current flows in an inductor?

If during self-induction the inductor produces a current in opposite direction of that of battery in order to resist the change of current through it then how could the current after some reasonable ...
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Inductor in a DC circuit [closed]

I found this question, I don't understand how could the current through 2R ,immediately after opening the circuit, be less than when the circuit is closed! Shouldn't be an emf from the inductor that ...
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How should I express the force field acting on a ring in Thomson's jumping ring experiment?

I did Thomson's Jumping Ring Experiment with some additional factors added. I used aluminium rings of the same inner diameter, same thickness (at 2 mm), but varying outer diameter (starting from 65 mm ...
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Velocity attained by a Loop with an induced current

A rectangular loop of resistance R is kept at a certain distance from an infinite straight current carrying conductor. The current is suddenly switched off. The problem was to find the velocity ...
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Electrical generators: power balance

Usually power generating synchronous generators are rated at around 85-90% efficiency. Curiosity struck me as of how a generator with field coils can ever go to such an high efficiency. My thought ...
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Current induced from a changing magnetic field

This question is motivated by Problem 7.12 in Griffiths Electrodynamics book. I have already solved the question, so there is no issue with homework policy. Relevant Equations: $$\Phi = \int{\vec{B}\...
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Inductors in Transformers

Why is it the flux change which induces the ac current of primary coil equal to the flux change that primary coil induces on the secondary coil? Is it possible to prove this? slide from video ...